It is common for an owner of a vehicle, such as an automobile, truck or the like, to tow or trail various trailers, such as a camper trailer, a boat trailer, a storage trailer, or the like. Electrical power is made available to the trailer by an electrical connector that electrically connects the towing vehicle's electrical supply system to a trailer electrical system.
The trailer electrical system can include, for example, a right turn/stop lamp and a left/turn stop lamp. When either of the lamps fail due to, for example, an open filament, the vehicle operator is most often unaware of the failure. It is not until other bystanders notify the operator or the operator performs an inspection while the trailer is in a parked condition that the operator becomes aware of the failure.